A golden product is a product that has zero defect. In the semiconductor manufacturing industry, it is often difficult to manufacture a golden product because of unavoidable defects in the fabrication process. Defects in a product are typically measured in terms of a defect density, which represents the number of defects detected in a given area of the product. In order to approach or achieve the production of a golden product, a reduction in defect density is necessary. However, the reduction of defect density is often difficult to achieve because different products may have different defect density improvement rates. For example, a large die product may show a better product yield than a smaller die product, even though both products' defect densities are reduced at a same rate. A need exists for a method that focuses defect density reduction on products that provide the best return-on-investment for the manufacturing facilities in order to generate a better product yield. A need also exists for a service model that gains better defect density and yield for products that are critical to the customers.